Servants will abandon a master who has lost his wealth, even if that master is a saintly person of exemplary character. Masters will abandon an incapacitated servant, even if that servant has been in the family for generations. Cows will be abandoned or killed when they stop giving milk.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
पतिं त्यक्ष्यन्ति निर्द्रव्यं भृत्या अप्यखिलोत्तमम् । भृत्यं विपन्नं पतयः कौलं गाश्चापयस्विनीः
patiṃ tyakṣyanti nirdravyaṃ bhṛtyā apyakhilottamam | bhṛtyaṃ vipannaṃ patayaḥ kaulaṃ gāścāpayasvinīḥ
SB 12.3.36